The overall goal of this proposal is to develop the new RF coil technology and physical understanding required to safely achieve the performance advantages inherent to high field NMR for biomedical research and diagnostics. Because the University of Minnesota and its Center for Magnetic Resonance Research are unique with their complement of 4T, 7T and 9.4T whole body magnet platforms, an unprecedented opportunity is now afforded to develop a continuum of engineering solutions and physical data for the upper spectrum of high field systems and applications. This goal continues from the original grant's aims to advance human head and brain imaging to 7T. With the original aims largely met, the objective of the present proposal for continuation expands on the original research in three ways. 1.) New theoretical models will be developed for RF propagation and loss to 400 MHz (9.4T). 2.) Based on these model results, new approaches will be developed for RF parameter optimization at the highest fields. 3.) These innovative RF optimization approaches will be realized in innovative new technologies for body imaging to 7T and for head imaging to 9.4T.